The fact that Rob Gronkowski has missed five games to start this NFL season and will miss a sixth Sunday against the Saints, according to multiple reports, shouldn’t come as much of a surprise to anyone who has followed his medical history the past 10 months.

The injury keeping him off the field, though, is the real shocker — and it instills a lot of doubt that he’ll be the “same old Gronk” anytime soon, if ever.

The surgery Gronkowski had June 18 to repair a herniated disk in his back was presumed to be the procedure that would delay his return to the field. The typical recovery period is about 12 weeks, which matched up right around Week 1.

Given Gronkowski’s injury history and importance to the team, it was easy to think the Patriots would hold him out a little longer to make sure he regained his strength and was ready to take NFL hits.

But it’s not his back keeping him out of the lineup. Instead, it’s the left forearm — the one that was operated on four times in the last 10 months because of an infection that developed in the area.

Gronkowski’s last forearm operation was in May, nearly five months ago, and was supposed to fix the bone and eradicate the infection. Yet here we are, in Week 6 of the season, and Gronkowski is still not ready to play.

I’m no doctor, but broken bones usually heal within five months.

It’s hard to know exactly what is going on with Gronkowski, given that he and the Patriots aren’t saying much, as usual.

On Friday, a report from WEEI said Gronkowski’s camp has “serious concern” over the way Patriots team doctor Thomas Gill handled the initial forearm surgery, after which Gronkowski rebroke the bone and developed the infection.

ESPN reported Friday that Gronkowski hadn’t received clearance to play by his hand-picked medical team of Dr. James Andrews, who consulted on Gronkowski’s last arm surgery, and orthopedic surgeon Dr. Jesse Jupiter, who performed the surgery at Massachusetts General Hospital.

A league source told the Globe Friday that the decision to return to the field is mostly up to Gronkowski, and the team is understanding of that. The team has cleared Gronkowski to return, and Gronkowski’s agent, Drew Rosenhaus, uses Andrews for many of his second opinions. But in this case, Andrews is not an expert in forearm injuries and will likely not be the one to clear Gronkowski to play again, according to the league source.

Gronkowski’s camp has advised the tight end to be cautious and listen to the advice of Andrews, but Andrews won’t be the one who says go play, the source said.

Gronkowski initially broke the bone last Nov. 18 against the Colts, but instead of letting the bone heal naturally, he and Gill decided to speed up the healing process by implanting a device in the forearm.

Dr. Tamara Rozental, an orthopedic surgeon at Beth Israel Deaconess Medical Center who specializes in hand, wrist, and elbow injuries, said a plate and screws are often used to compress a fracture and keep the bone in place to help it heal more quickly. But with a foreign object in your body, “when you do get an infection, it’s a much more difficult problem to treat,” said Rozental, who has not treated Gronkowski.

The risk of infection is greater with each surgery done to the area, Rozental said.

Gronkowski returned to the field at the end of December but broke the bone again in January, and had three more surgeries to clean out the infection. According to the WEEI report, Gronkowski’s camp has concerns about the integrity of the bone where the implement was placed and the surrounding nerves, and that the infection may have been avoided if the bone had healed on its own.

But if Gronkowski is still having concerns five months after his last surgery, this raises serious questions about his long-term viability. He broke the bone again just two weeks after returning to the field, and if it has indeed been weakened by this infection, how long will it be until he breaks it again? Will he ever be able to last a full NFL season again?

One aspect of this that the Patriots definitely handled correctly was keeping Gronkowski off the physically unable to perform list. Putting Gronkowski on PUP would have opened up a roster spot for six weeks, but also would have prevented him from practicing with the team.

He would have been permitted only to work with team trainers, and by rule would have had to sit out the first six games. By being off PUP, Gronkowski was able to practice with his teammates, could return to the lineup whenever he felt ready, and gave opponents something to think about each week, even if the Patriots knew he wouldn’t be playing.

But the Patriots clearly thought Gronkowski would be ready to go by now. They thought he could have been ready to play as early as Week 3 against Tampa Bay, and the amount he has practiced over the last three weeks has led teammates to believe that he would be in the lineup already.

At some point, Gronkowski may just have to suck it up and play, even if he’s not 100 percent confident in his forearm. The Patriots gave him an $8 million signing bonus last year, and it wasn’t to sit around in the training room.

His team needs him badly, as evidenced by the 6 points it totaled against Cincinnati last week. The Patriots are 31st in the NFL in red-zone scoring (touchdowns on 35 percent of possessions), and Gronkowski certainly would improve that.

Playing through injuries is common in the NFL, and Gronkowski’s team needs him. If the bone is still damaged five months after surgery, who’s to say it’s going to get stronger anytime soon?

If he happens to break the bone again? That’s a matter between the player, the team, and possibly an arbitration court. Of course, it’s unlikely that Gill implanted the device in Gronkowski’s forearm without the player’s consent.

Gronkowski has to look out for himself first and foremost, but at some point soon, an obligation to his teammates and fans must get him back on the football field.